Method of forming a gasket for automotive lamps

ABSTRACT

An automotive lamp which includes a lamp body, a gasket disposed between the lamp body and an automobile body panel for sealing a back side of the lamp, a seal leg projecting from the lamp body for attaching thereto the gasket, wherein the foamed gasket is molded integrally with a tip end part of the seal leg.

This is a divisional of application Ser. No. 08/703,781 filed Aug. 27,1996, now U.S. Pat. No. 5,993,036 the disclosure of which isincorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an automotive lamp in which a gasketfor sealing a back side of the lamp is disposed between a lamp body andan automobile body panel so that water, dusts and the like are preventedfrom entering the back side of the lamp where wires connecting to a lampbulb or the other electrical equipment are arranged.

2. Related Art

FIG. 5 is a vertical sectional view showing a conventional automotivelamp of the type as disclosed, for example, in Unexamined JapanesePatent Publication No. Hei. 3-15748. The conventional automotive lampshown in FIG. 5 includes a lamp body 1 which is formed on a back wallthereof with a seal leg 2 projecting therefrom for surrounding a bulbinsertion hole 2 and a gasket 8 disposed between the seal leg 2 and anautomobile body panel 6. Both a front and a rear side of the gasket 8have a respective high adhesive surface so that the gasket 8 sticks bothto the seal leg 2 and the automobile body panel 6. In the figure,reference numeral 3 designates a front lens and reference numeral 4designates a lamp bulb.

FIG. 6 is a sectional view of an essential part of another conventionalautomotive lamp. As shown in FIG. 6, a gasket 8A is formed like anendless web a cross section of which is U-shaped. An adhesive agent isapplied, if desirable, to a tip end of the seal leg 2 so that the gasket8A sticks to the seal leg 2.

According to the conventional gasket 8 as described above and shown inFIG. 5, however, since the gasket 8 is formed by cutting out a seat-likematerial to have a frame-shape to fit to the configuration of the tipend of the seal leg 2, the yield rate of the material is veryunsatisfactory which raises manufacturing cost.

Further, the high adhesive surfaces of the gasket 8 shown in FIG. 5 areactually made from a double-sided adhesive tape. More specifically, thedouble-sided adhesive tape with a peel-off sheet on each side isattached to each the front and rear surfaces of the gasket 8.Accordingly, during assembly of the conventional automotive lamp, whenthe lamp is coupled to the automobile body, the gasket 8 is disposedbetween the seal leg 2 and the automobile body panel 6. First, thepeel-off sheet on one side of the gasket 8 is peeled off to expose theadhesive surface, and then the adhesive surface is pressed against theseal leg 2 so that the gasket 8 sticks integrally to the seal leg 2.Next, the peel-off sheet of the other side of the gasket 8 is peeledoff, and then the lamp is coupled to the automobile body, so that theadhesive surface of the gasket 8 sticks to the automobile body panel 6.Thus, the conventional automotive lamp requires the complicated stepsduring assembly, which steps takes a relatively long time. That is aproblem because it raises the manufacturing cost.

On the other hand, according to the secondary conventional gasket 8Ashown in FIG. 6, the gasket 8A is formed by the injection moldingoperation, and the cost for the mold die apparatus or the like is veryhigh. In addition, the gasket 8A must be attached to the seal leg 2prior to coupling the lamp to the automobile body. This is intricate.Further, in a case where no adhesive agent is applied to the tip end ofthe seal leg 2, the gasket 8A may sometimes drop off the seal leg 2.

SUMMARY OF THE INVENTION

The present invention was made in view of the foregoing difficulties andproblems accompanying the conventional automotive lamps. Therefore, anobject of the present invention is to provide an automotive lamp capableof simplifying coupling operation during assembly as well as improvingthe yield rate of materials for a gasket which is disposed between aseal leg and an automobile body panel.

The above and other objects can be achieved by a provision of anautomotive lamp which, according to the invention, includes a lamp body,a gasket disposed between the lamp body and an automobile body panel forsealing a back side of the lamp, a seal leg projecting from the lampbody for attaching thereto the gasket, wherein the foamed gasket ismolded integrally with a tip end part of the seal leg. Since the gasketis foam-molded integrally with the seal leg projecting from the lampbody and thereby in close-contact with to the seal leg, it is notnecessary to adhere the gasket to the seal leg by an adhesive agent orthe like.

According to another aspect of the present invention, first, a nozzleinjects a material for a foamed gasket into a gasket molding grooveformed in a jig, and the injected material is left to therebyfoam-expand. Next, a lamp body with a seal leg facing down is operatedto move downward so that the seal leg is inserted in the molding groove,and the seal leg is held against the gasket material. As a result, thesurface of the gasket is solidified. Afterwards, the gasket is releasedfrom the jig together with the lamp body and the seal leg, and thegasket is left in atmosphere so that the gasket is sufficientlysolidified. Thus, the gasket is molded integrally with the seal leg.

Among these steps, if desired, the step in which the nozzle injects thegasket material, the step in which the lamp body is moved down topress-fit the seal leg into the foamed gasket material filled in themolding groove, and the step in which the lamp body is lifted to releasethe gasket from the molding groove together with the seal leg may beautomated. If these steps are automated, an operator has to merely setthe lamp body on an automation line and take the lamp body which ismolded integrally with the gasket out of the automated product line.Hence, mass-production can be achieved while excessively reducing themanual works.

Further, if the seal leg is subjected to surface active treatment, thegasket would hardly detach from the seal leg because of the highadhesibility of the foamed gasket to the seal leg. As a result, easytreatment of the lamp with which the gasket is integrated, improvedoperation for coupling the lamp to the vehicle body, and goodworkability when the gasket is provided can be accomplished.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a vertical sectional view showing a clearance lamp to which afirst embodiment of the present invention is applied;

FIG. 2 is a partly cut away perspective view of a lamp body of theclearance lamp shown in FIG. 1;

FIGS. 3A, 3B, 3C and 3D are views for explaining steps of unitarilyattaching a gasket to a seal leg;

FIG. 4 is a vertical sectional view showing a clearance lamp to which asecond embodiment of the present invention is applied;

FIG. 5 is a sectional view showing a conventional automotive lamp; and

FIG. 6 is a sectional view of an essential part of another conventionalautomotive lamp.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention will now be described with reference toaccompanying drawings.

FIGS. 1 through 3 show a clearance lamp for automobiles to which a firstembodiment of the present invention is applied. More specifically, FIG.1 is a vertical sectional view showing a clearance lamp to which a firstembodiment of the present invention is applied, FIG. 2 is a partly cutaway perspective view of a lamp body of the clearance lamp shown in FIG.1, and FIGS. 3A, 3B, 3C and 3D are views for explaining steps ofunitarily attaching a gasket to a seal leg.

As shown in the figures, the clearance lamp is provided with acup-shaped lamp body 10 having a parabolic reflector 10 a formed on aninner surface thereof, a front lens 12 coupled to a front opening of thelamp body 10, a bulb insertion hole 11 formed in a rear peak of the lampbody 10, and a lamp bulb 14 serving as a light source mounted on thebulb insertion hole 11.

A seal leg 16 extends backward from a back wall of the lamp body 10 insuch a manner that the seal leg 16 surrounds the bulb insertion hole 11.A foamed gasket 20 is disposed between a tip end part 16 a of the sealleg 16 and an automobile body panel 18. The foamed gasket 20 is moldedintegrally with the tip end part 16 a of the seal leg 16. With thisstructure, the foamed gasket 20 has a highly tight connection withrespect to the seal leg 16, and the gasket 20 hardly detaches from theseal leg 16 of the lamp body 10.

According to the present invention, it is not necessary to stick agasket to a seal leg by using a double-sided adhesive tapes or anadhesive agent as required by the conventional gaskets. In addition, itis quite simple and easy to dispose the gasket between the seal leg andthe automobile body panel during the assembly of the lamp.

That is, since the gasket 20 is previously molded integrally with theseal leg 16 according to the present invention, the gasket 20 can bedisposed between the seal leg 16 and the automobile body panel 18 at thesame time when the lamp is coupled to the automobile body. In otherwords, when the lamp is mounted on the automobile body, the gasket 20automatically comes to a condition where the gasket 20 is press-fittedbetween the seal leg 16 and the automobile body panel 18.

Further, since the gasket 20 is molded integrally with the seal leg 16,the gasket 20 is accurate in dimension and presents a flat surface.Accordingly, the gasket 20 has improved capability for close-contact,i.e., the gas sealability, with respect to the automobile body panel 18and, therefore, water or dust is securely prevented from entering theback side of the lamp from the front side thereof.

The steps of integrally molding the gasket 20 with the seal leg 16 willnow be described with reference to FIGS. 3A through 3D. A referencenumeral 30 in FIGS. 3A to 3D designates a jig for transfer made from aflat metal plate and which is laid horizontally. A groove 32 for moldingthe gasket is formed in a front surface of the jig 30. The moldinggroove 32 extends along the same shape as the seal leg 16 and receivesthe same. A release agent is applied onto an inner surface of the groove32.

First, a nozzle 34 injects material for the foamed gasket into thegroove 32 of the jig 30 as shown in FIG. 3A, and the injected materialis left for sever seconds to thereby foam-expand the material for gasketas shown in FIG. 3B. Next, the lamp body 10 with the seal leg facingdown is operated to move downward so that the seal leg 16 is inserted inthe molding groove 32 as shown in FIG. 3C, and the seal leg 16 is heldpressing against the gasket material for a predetermined time period(several seconds). As a result, the surface of the gasket 20 issolidified. Afterwards, as shown in FIG. 3D, the gasket 20 is releasedfrom the jig 30 together with the lamp body 10 and the seal leg 16, andthe gasket is left at atmospheric pressure for a predetermined timeperiod (several seconds), so that the gasket 20 is sufficientlysolidified. Thus, the gasket 20 is molded integrally with the seal leg16.

In order to enhance the adhesibility of the gasket 20 to the seal leg16, if desired, the seal leg 16 is subjected to surface active treatmentsuch as primer, frame, ultra violet(UV), corona, plasma treatment or thelike.

A resin material such as acrylonitrile-butadiene-styrene (ABS),acrylonitrile-acryl rubber-styrene (AAS), polymethylmethacrylate (PMMA),polypropylene (PP) or the like may be employed as the material of thelamp body 10 and the seal leg 16. On the other hand, a foamed materialwhich is based on polyester, one-liquid urethane, two-liquid urethane,silicone resin or the like may be selected as a material of the foamedgasket. The material of the foamed gasket may preferably haveheat-resistivity at 80° C. so that the gasket can maintain reliabilityeven when subject to heat generated by the lamp bulb of the lamp.

Among the molding steps shown in FIGS. 3A through 3D, the FIG. 3A stepin which the nozzle 34 injects the gasket material, the FIG. 3C step inwhich the lamp body 10 is operated to move downward to press-fit theseal leg 16 into the foamed gasket material filled in the molding groove32, and the FIG. 3D step in which the lamp body 10 is lifted to releasethe gasket 20 from the molding groove 32 together with the seal leg 16may be automated. If these steps are automated, an operator has tomerely set the lamp body 10 on an automated product line and take thelamp body 10 which is molded integrally with the gasket 20 out of theautomated line. Hence, mass-production can be achieved while excessivelyreducing the manual works.

FIG. 4 is a vertical sectional view showing a clearance lamp to which asecond embodiment of the present invention is applied.

In the first embodiment described above, the seal leg 16 is disposed ata peripheral position on the back wall of the lamp body 10 in such amanner that the seal leg 16 surrounds the bulb insertion hole 11. In thesecond embodiment, however, a seal leg 17 projects from and extendsalong a bottom of a seal groove 13 formed in a periphery of the frontopening of the lamp body 10 as shown in FIG. 4. The foamed gasket 20 ismolded integrally with a tip end part 17 a of the seal leg 17.

The other structures of the second embodiment are the same as those ofthe first embodiment described above and, accordingly, the descriptionof which is omitted here.

As described above, according to the automotive lamp of the presentinvention, a gasket can be molded integrally with a seal leg merely byinserting the seal leg into a foamed gasket material injected into amolding groove. Therefore, the present invention greatly improves theyield rate of the gasket material, and reduces the cost for the gasket,which in turn reduces the cost for the lamp.

Further, because the gasket is securely integrated with the seal leg,and because the gasket automatically becomes press-fitted between theseal leg and the automobile body panel at the same time the lamp iscoupled to the automobile body, the workability is much improved.

The gasket tightly-contacts to the seal leg and the automobile bodypanel when the lamp is coupled to the automobile body. Therefore, thesufficient sealability of the gasket can be maintained compared with theconventional gasket.

Incidentally, when the gasket is molded integrally with the tip end partof the seal leg, some of the molding steps can be readily automated. Ifsome steps are automated, mass-production of the lamps can be achievedwhile excessively reducing the manual works.

In addition, if the seal leg is subjected to the surface activetreatment, the gasket would hardly detach from the seal leg because ofthe high adhesibility of the foamed gasket to the seal leg. As a result,easy treatment of the lamp with which the gasket is integrated, improvedoperation for coupling the lamp to the automobile body, and goodworkability when the gasket is fitted, can be accomplished.

It should be understood that the form of the invention herein shown anddescribed is to be taken as a preferred example of the invention andthat various changes in the shape, size and arrangement of parts may beresorted to without departing from the spirit of the invention or thescope of the subjoined claims.

What is claimed is:
 1. A method of molding a gasket disposed between alamp body and an automobile body panel, the gasket being moldedintegrally with a seal leg of the lamp body, wherein the lamp body isnot a lamp lens, the molding method comprising the steps of: preparing ajig in which a gasket molding groove is formed; injecting a moldmaterial into the molding groove of the jig; inserting a seal leg of thelamp body into the molding groove and holding the same therein;solidifying the mold material; and releasing the seal leg of the lampbody together with the gasket from the molding groove of the jig.
 2. Themolding method according to claim 1, wherein the mold material is afoamed material.
 3. The molding method according to claim 2, wherein thefoamed material of said gasket is based on one of polyester, one-liquidurethane, two-liquid urethane and silicone resin.
 4. The molding methodaccording to claim 1, wherein said lamp body and said seal leg areformed from resin material.
 5. The molding method according to claim 4,wherein the resin material for said lamp body and said seal leg isselected from a group consisting of ABS, AAS, PMMA and PP.
 6. Themolding method according to claim 1, wherein said gasket materialinjecting step, said seal leg inserting step, and said releasing stepare automated.
 7. The molding method according to claim 1, wherein saidseal leg projects from and extends along a bottom of a seal grooveformed in a periphery of a front opening of said lamp body.
 8. Themolding method according to claim 1, wherein the material of said gaskethas a heat-resistivity.
 9. The molding method according to claim 1,further comprising a step of applying a release agent onto an innersurface of the gasket molding groove, wherein said step of applying arelease agent is performed after said step of preparing a jig but beforesaid step if injecting a mold material into the molding groove of thejig.
 10. A method of molding a gasket disposed between a lamp body andan automobile body panel, the gasket being molded integrally with a sealleg of the lamp body, the molding method comprising the steps of:preparing a jig in which a gasket molding groove is formed; injecting amold material into the molding groove of the jig; inserting a seal legof the lamp body into the molding groove and holding the same therein;solidifying the mold material; releasing the seal leg of the lamp bodytogether with the gasket from the molding groove of the jig; andsubjecting a surface active treatment to said seal leg of the lamp bodyprior to said step of inserting said seal leg into the molding groove.11. The molding method according to claim 10, wherein the surface activetreatment is selected from the group consisting of primer, flame, UV,corona and plasma treatment.
 12. A method of molding a gasket disposedbetween a lamp body and an automobile body panel, the gasket beingmolded integrally with a seal leg of the lamp body, the molding methodcomprising the steps of: preparing a jig in which a gasket moldinggroove is formed; injecting a mold material into the molding groove ofthe jig; inserting a seal leg of the lamp body into the molding grooveand holding the same therein; solidifying the mold material; andreleasing the seal leg of the lamp body together with the gasket fromthe molding groove of the jig, wherein said seal leg projects from aback wall of said lamp body to surround a bulb insertion hole formed insaid lamp body.